Method and device for controlling rrc state mismatch issue in next-generation mobile communication system

ABSTRACT

The present disclosure relates to a communication technique for converging IoT technology with a 5G communication system for supporting a higher data transmission rate beyond a 4G system, and a system therefor. The present disclosure may be applied to an intelligent service (for example, a smart home, a smart building, a smart city, a smart car or connected car, health care, digital education, retail business, a security and security-related service, etc.) on the basis of 5G communication technology and IoT-related technology. The present disclosure discloses a method and a device for controlling the RRC state mismatch issue of a terminal, and also discloses a method and a device for providing access control configuration information of a terminal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 17/053,322,now U.S. Pat. No. 11,457,400, which is the 371 National Stage ofInternational Application No. PCT/KR2019/005557, filed May 9, 2019,which claims priority to Korean Patent Application No. 10-2018-0053358,filed May 9, 2018, the disclosures of which are herein incorporated byreference in their entirety.

BACKGROUND 1. Field

The disclosure relates to a wireless communication system and, moreparticularly, to a method and device for controlling a mismatch (ordiscrepancy) in radio resource control (RRC) state which may occur in anext generation communication system.

2. Description of Related Art

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a “Beyond 4G Network” or a“Post LTE System”.

The 5G communication system is considered to be implemented in higherfrequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higherdata rates. To decrease propagation loss of the radio waves and increasethe transmission distance, the beamforming, massive multiple-inputmultiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antenna,an analog beam forming, large scale antenna techniques are discussed in5G communication systems.

In addition, in 5G communication systems, development for system networkimprovement is under way based on advanced small cells, cloud radioaccess networks (RANs), ultra-dense networks, device-to-device (D2D)communication, wireless backhaul, moving network, cooperativecommunication, coordinated multi-points (CoMP), reception-endinterference cancellation and the like.

In the 5G system, hybrid FSK and QAM modulation (FQAM) and slidingwindow superposition coding (SWSC) as an advanced coding modulation(ACM), and filter bank multi carrier (FBMC), non-orthogonal multipleaccess(NOMA), and sparse code multiple access (SCMA) as an advancedaccess technology have also been developed.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the Internetof things (IoT) where distributed entities, such as things, exchange andprocess information without human intervention. The Internet ofeverything (IoE), which is a combination of the IoT technology and thebig data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology”,“wired/wireless communication and network infrastructure”, “serviceinterface technology”, and “security technology” have been demanded forIoT implementation, a sensor network, a machine-to-machine (M2M)communication, machine type communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected things. IoT maybe applied to a variety of fields including smart home, smart building,smart city, smart car or connected cars, smart grid, health care, smartappliances and advanced medical services through convergence andcombination between existing information technology (IT) and variousindustrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, machine type communication (MTC), andmachine-to-machine (M2M) communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud radioaccess network (RAN) as the above-described big data processingtechnology may also be considered an example of convergence of the 5Gtechnology with the IoT technology.

Due to various situations that may happen in a next generationcommunication system, mismatching or discrepancy in RRC state of a UEmay occur. Accordingly, a demand for a method of controlling themismatch problem is increasing.

SUMMARY

Therefore, the disclosure has been made in view of the above-mentionedproblems, and an aspect of the disclosure is to improve a communicationenvironment between a user equipment (UE) and a base station (BS) byovercoming a mismatch in radio access state which may occur between theUE and the BS.

Another aspect of the disclosure is to provide a stable communicationenvironment between a BS and a UE by controlling connection (access) ofthe UE.

In accordance with an aspect of the disclosure, a method of overcomingthe above-mentioned problem by a user equipment (UE) may include:identifying a network to access via a base station (BS); receiving afirst system information block (SIB) including first information foraccess control, from the BS if the network is a first network; receivinga second SIB including second information for access control, from theBS if the network is a second network; and performing access controlbased on the first information included in the first SIB if the networkis the first network; and performing access control based on the secondinformation included in the second SIB if the network is the secondnetwork.

In accordance with another aspect of the disclosure, a method ofovercoming the above-mentioned problem by a BS may include:transmitting, to a UE, a first SIB including first information foraccess control; and transmitting, to the UE, a second SIB includingsecond information for access control, wherein if the network to whichthe UE is to access is a first network, access control is performedusing the first information included in the first SIB, and if thenetwork to which the UE is to access is a second network, access controlis performed using the second information included in the second SIB.

In accordance with another aspect of the disclosure, a UE for overcomingthe above-mentioned problem according to an embodiment may include: atransceiver configured to transmit and receive a signal; and acontroller configured to: identify a network to access via a BS; receivea first SIB including first information for access control from the BSif the network is a first network; receive a second SIB including secondinformation for access control from the BS if the network is a secondnetwork; perform access control based on the first information includedin the first SIB if the network is the first network; and perform accesscontrol based on the second information included in the second SIB ifthe network is the second network.

In accordance with another aspect of the disclosure, a BS for overcomingthe above-mentioned problem according to an embodiment may include: atransceiver configured to transmit and receive a signal; and acontroller configured to transmit a first SIB including firstinformation for access control to a UE, and configured to transmit asecond SIB including second information for access control to the UE,wherein, if a network to which the UE is to access is a first network,access control is performed using the first information included in thefirst SIB, and if a network to which the UE is to access is a secondnetwork, access control is performed using the second informationincluded in the second SIB.

According to an embodiment of the disclosure, a mismatch (discrepancy)in RRC state between a user equipment (UE) and a base station (BS) isovercome, and thus the UE and the BS can efficiently communicate witheach other.

According to another embodiment of the disclosure, a network accessprocess of a UE is enhanced, and thus a stable communication environmentcan be provided between the UE and a network.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagram illustrating the structure of a next generationmobile communication system;

FIG. 1B is a diagram illustrating transition of a radio access state ina next generation mobile communication system;

FIG. 1C is a diagram illustrating a mismatch in radio access state in anext generation mobile communication system;

FIG. 1D is a flowchart illustrating a process of overcoming a mismatchin radio access state, according to an embodiment of the disclosure;

FIG. 1E is a flowchart illustrating operation of a user equipment (UE)according to an embodiment of the disclosure;

FIG. 1F is a flowchart illustrating operation of a base station (BS)according to an embodiment of the disclosure;

FIG. 1G is a flowchart illustrating a process of transmitting an ACKsignal by a UE if the UE receives a connection release message accordingto an embodiment of the disclosure;

FIG. 1H is a block diagram illustrating the internal structure of a UEaccording to an embodiment of the disclosure;

FIG. 1I is a block diagram illustrating the configuration of a BSaccording to an embodiment of the disclosure;

FIG. 2A is a diagram illustrating an LTE BS connected to a nextgeneration mobile communication network;

FIG. 2B is a diagram illustrating a process of performing UE accesscontrol in an LTE system;

FIG. 2C is a diagram illustrating a process of performing UE accesscontrol in a next generation mobile communication system;

FIG. 2D is a flowchart illustrating an operation of providing accessconfiguration information by a BS according to an embodiment of thedisclosure;

FIG. 2E is a flowchart illustrating an operation of receiving andapplying access configuration information by a UE according to anembodiment of the disclosure;

FIG. 2F is a block diagram illustrating the internal structure of a UEaccording to an embodiment of the disclosure; and

FIG. 2G is a block diagram illustrating the configuration of a BSaccording to an embodiment of the disclosure.

DETAILED DESCRIPTION

Hereinafter, embodiments of the disclosure will be described in detailwith reference to the accompanying drawings. It should be noted that, inthe drawings, the same or like elements are designated by the same orlike reference signs as much as possible. Further, a detaileddescription of known functions or configurations that may make thesubject matter of the disclosure unclear will be omitted.

In describing embodiments of the disclosure, descriptions related totechnical contents well-known in the art and not associated directlywith the disclosure will be omitted. Such an omission of unnecessarydescriptions is intended to prevent obscuring of the main idea of thedisclosure and more clearly transfer the main idea.

For the same reason, in the accompanying drawings, some elements may beexaggerated, omitted, or schematically illustrated. Further, the size ofeach element does not completely reflect the actual size. In thedrawings, identical or corresponding elements are provided withidentical reference numerals.

The advantages and features of the disclosure and ways to achieve themwill be apparent by making reference to embodiments as described belowin detail in conjunction with the accompanying drawings. However, thedisclosure is not limited to the embodiments set forth below, but may beimplemented in various different forms. The following embodiments areprovided only to completely disclose the disclosure and inform thoseskilled in the art of the scope of the disclosure, and the disclosure isdefined only by the scope of the appended claims. Throughout thespecification, the same or like reference numerals designate the same orlike elements.

Here, it will be understood that each block of the flowchartillustrations, and combinations of blocks in the flowchartillustrations, can be implemented by computer program instructions.These computer program instructions can be provided to a processor of ageneral purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions, which execute via the processor of the computer orother programmable data processing apparatus, create means forimplementing the functions specified in the flowchart block or blocks.These computer program instructions may also be stored in a computerusable or computer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer usable orcomputer-readable memory produce an article of manufacture includinginstruction means that implement the function specified in the flowchartblock or blocks. The computer program instructions may also be loadedonto a computer or other programmable data processing apparatus to causea series of operational steps to be performed on the computer or otherprogrammable apparatus to produce a computer implemented process suchthat the instructions that execute on the computer or other programmableapparatus provide steps for implementing the functions specified in theflowchart block or blocks.

Further, each block of the flowchart illustrations may represent amodule, segment, or portion of code, which includes one or moreexecutable instructions for implementing the specified logicalfunction(s). It should also be noted that in some alternativeimplementations, the functions noted in the blocks may occur out of theorder. For example, two blocks shown in succession may in fact beexecuted substantially concurrently or the blocks may sometimes beexecuted in the reverse order, depending upon the functionalityinvolved.

As used herein, the “unit” refers to a software element or a hardwareelement, such as a Field Programmable Gate Array (FPGA) or anApplication Specific Integrated Circuit (ASIC), which performs apredetermined function. However, the “unit” does not always have ameaning limited to software or hardware. The “unit” may be constructedeither to be stored in an addressable storage medium or to execute oneor more processors. Therefore, the “unit” includes, for example,software elements, object-oriented software elements, class elements ortask elements, processes, functions, properties, procedures,sub-routines, segments of a program code, drivers, firmware,micro-codes, circuits, data, database, data structures, tables, arrays,and parameters. The elements and functions provided by the “unit” may beeither combined into a smaller number of elements, or a “unit”, ordivided into a larger number of elements, or a “unit”. Moreover, theelements and “units” or may be implemented to reproduce one or more CPUswithin a device or a security multimedia card.

First Embodiment

FIG. 1A is a diagram illustrating the structure of a next generationmobile communication system.

Referring to FIG. 1A, a radio access network of a next generation mobilecommunication system (e.g., a new radio (NR)) includes a next generationbase station (i.e., a new radio NodeB, hereinafter, a gNB) 1 a-10 and anaccess management function (AMF) 1 a-05 (i.e., a new radio corenetwork). A user equipment (i.e., a new radio user equipment (NR UE) (ora UE)) 1 a-15 may access an external network via the gNB 1 a-10 and theAMF 1 a-05.

In FIG. 1A, the gNB may corresponds to an evolved nodeB (eNB) of alegacy LTE system. The gNB is connected to the NR UE via a wirelesschannel, and may provide a better service than a service provided by alegacy nodeB in operation 1 a-20. In the next generation mobilecommunication system, all user traffic is serviced via a shared channel.Accordingly, a device may be needed that performs scheduling bycollecting state information associated with UEs such as a buffer state,an available transmission power state, a channel condition, and thelike. The gNB 1 a-10 takes charge of the same. One gNB generallycontrols a plurality of cells. In order to implement ultra-high speeddata transmission when compared to the legacy LTE, the NR system mayhave a bandwidth greater than or equal to the current maximum bandwidth,and may additionally use a beamforming technology by using an orthogonalfrequency division multiplexing (OFDM) as a radio access technology.Also, the NR system applies an adaptive modulation & coding (AMC) schemethat determines a modulation scheme and a channel coding rate based onthe channel state of a UE. The AMF 1 a-05 performs a function ofsupporting mobility, configuring a bearer, configuring a QoS, and thelike. The AMF is a device that is in charge of various controlfunctions, in addition to a mobility management function associated witha UE, and may be connected to a plurality of BSs. In addition, the nextgeneration mobile communication system may interoperate with a legacyLTE system, and an AMF is connected to an MME 1 a-25 via a networkinterface. The MME is connected to an eNB 1 a-30 which is a legacy basestation. A UE that supports LTE-NR dual connectivity maintains aconnection to an eNB, in addition to a connection to a gNB, and maytransmit and receive data in operation 1 a-35.

FIG. 1B is a diagram illustrating transition of a radio access state ina next generation mobile communication system.

In a legacy LTE system, a UE may have two types of radio access states,that is, a connected mode 1 b-35 and an idle mode 1 b-45. Two modes maybe changed via an establishment procedure and a release procedure inoperation 1 b-40. Conversely, in the next generation mobilecommunication system, the UE may have three types of radio access states(RRC states). A connected mode (RRC_CONNECTED) 1 b-05 is a radio accessstate in which a UE is capable of performing data transmission andreception with a gNB. An idle mode (RRC_IDLE) 1 b-30 is a radio accessstate in which a UE monitors whether paging is transmitted to the UE.The two modes are radio access states that may be also applied to thelegacy LTE system, and the detailed description thereof is the same asthat of the legacy LTE system. In the next generation mobilecommunication system, an inactive mode (RRC_INACTIVE) radio access state1 b-15 is newly defined. In the radio access state, UE context ismaintained in a gNB and a UE, and RAN-based paging is supported. Thefeatures of the new radio access state are as follows.

-   -   Cell re-selection mobility;    -   CN—NR RAN connection (both C/U-planes) has been established for        UE;    -   The UE AS context is stored in at least one gNB and the UE;    -   Paging is initiated by NR RAN;    -   RAN-based notification area is managed by NR RAN;    -   NR RAN knows the RAN-based notification area which the UE        belongs to;

Among the features, an RAN-based notification area is an area configuredwith one or more cells, and RAN paging with respect to a predeterminedUE is transmitted in the area. Therefore, if the RAN area is changed asa UE moves, this may be reported to a gNB. The operation of reportingthe same is referred to as “RAN notification area (RNA) update”. Theoperation is performed periodically or when a UE moves to a cell belongto another RAN area. If the operation is performed periodically, theoperation is referred to as “periodic RNA update”. Since a UE is capableof moving, a cell that triggers the periodic RAN update and a cell thatreceives a report associated with the same may be different from eachother. Therefore, the cell that receives the report may forward theperiodic RNA update to the cell that performed triggering. Generally,the cell that performs triggering may have UE context of the UE, and maytransfer the UE context to the cell that performed forwarding.

The new INACTIVE radio access state may be changed to a connected modeor an idle mode using a predetermined procedure. A UE may be changedfrom the INACTIVE mode to the connected mode according to a connectionactivation procedure, and may be changed from the connected mode to theINACTIVE mode according to a connection inactivation procedure 1 b-10.The connection activation/inactivation procedure includes one or moreoperations of performing transmission and reception of one or more RRCmessages between a UE and a gNB. Similarly, the UE may be capable ofchanging from the INACTIVE mode to the idle mode according to apredetermined procedure 1 b-20. As the predetermined procedure, variousmethods such as a method of exchanging a predetermined message, atimer-based method, an event-based method, and the like, may beconsidered. Transition between the connected mode and the idle mode maybe performed according to the legacy LTE technology. That is, the modetransition may be performed via a connection establishment or releaseprocedure 1 b-25.

FIG. 1C is a diagram illustrating a mismatch in radio access state in anext generation mobile communication system.

A UE 1 c-05 is in the state of being connected to a gNB 1 c-10 inoperation 1 c-15. In the disclosure, the gNB transmits an RRC releasemessage to the UE in order to change the UE to an idle mode (RRC_Idle)or an inactive mode (RRC_Inactive). The message indicates UE'stransition to the idle mode or inactive mode, and may includeconfiguration information related thereto. The configuration informationmay be cell reselection priority information in the idle mode orinactive mode, a periodic RNA update timer value applied in the inactivemode, or the like. However, if a wireless channel has a poor condition,the UE may fail to receive the message in operation 1 c-20. The gNB mayregard that the UE is immediately changed to the idle mode or inactivemode, irrespective of reception of a HARQ feedback associated with themessage in operation 1 c-30. However, since the UE does not receive therelease message from the gNB, the UE may continuously maintain aconnected mode in operation 1 c-25. This phenomenon refers to a mismatchin radio access state.

FIG. 1D is a flowchart illustrating a process of overcoming a mismatchin radio access state, according to an embodiment of the disclosure.

A UE 1 d-05 receives the value of a first timer (e.g., the length of thefirst timer) and the value of a second timer (e.g., the length of thesecond timer) via a predetermined RRC message from a gNB 1 d-10 inoperation 1 d-15. The UE may operate the first timer at the point intime at which the timer value is received or at the point in time atwhich the timer value is received and first data is transmitted orreceived in operation 1 d-20, and may restart the timer in operation 1d-25 every time that the UE transmits or receives data in operation 1d-30. If the first timer expires, the UE may change from the connectedmode to the idle mode in operations 1 d-45 and 1 d-50. The UE and thegNB may operate the second timer at the point in time at which the timervalue is received or when the UE changes from the connected mode to theinactive mode, in operation 1 d-40. At a predetermined point in time,the gNB transmits, to the UE, a single RRC connection release messagethat requests RRC connection release, in operation 1 d-35. The messageindicates transition to the idle mode or inactive mode.

If the connection release message indicates the inactive mode, the gNBoperates the second timer in operation 1 d-40 when transmitting themessage. The message that requests RRC connection release may be usedfor providing the value of the second timer. The UE that receives theconnection release message may also operate the second timer. However,if the UE fails to receive the message, the first timer expires inoperation 1 d-45 and the UE may be changed to the idle mode in operation1 d-50. If the second timer expires in operation 1 d-55, the gNB mayexpect that “periodic RNA update” of the UE is received from the UE oran adjacent BS. After the second timer expires, the gNB may wait for theperiodic RNA update report during a predetermined period of time. If thegNB does not receive the “periodic RNA update” from the UE, the gNBdetermines that the UE does not receive the connection release message,and may regard that the UE is changed to the idle mode in operation 1d-60. If the first timer is still operating, the gNB regards that the UEis in the connected mode until the timer expires. Therefore, in thedisclosure, the “periodic RNA update” reported to the gNB may be used asfeedback information for determining whether the UE successfullyreceives the connection release message indicating the inactive mode. Ifthe “periodic RNA update” is not reported from the UE, the gNB mayregard that the UE is in the idle mode. If data is not transmitted orreceived until a predetermined timer expires, the UE may automaticallychange to the idle mode.

If the connection release message indicates an idle mode, the gNB mayregard that the UE is changed to the idle mode after a predeterminedperiod of time. In this instance, the gNB may not take intoconsideration whether the second timer operates or not. Therefore, inthe disclosure, the gNB may regards that the UE is changed to the idlemode, irrespective of whether the UE successfully receives theconnection release message indicating the inactive mode, and the UE alsoautomatically change to the idle mode if data is not transmitted orreceived until a predetermined timer expires.

In the disclosure, the first timer is referred to as a “data inactivitytimer” and the second timer is referred to as a “periodic RNA updatetimer”.

FIG. 1E is a flowchart illustrating operation of a UE according to anembodiment of the disclosure.

In operation 1 e-05, a UE receives configuration information associatedwith a first timer and a second timer from a BS. The configurationinformation may be the time values of the timers.

In operation 1 e-10, the UE may operate the first timer at the point intime at which the value of the first timer is received, or at the pointin time at which the timer value is received and first data istransmitted or received. The UE may operate the second timer at thepoint in time at which the value of the second timer is received, orwhen the UE changes from a connected mode to an inactive mode afterreceiving the timer.

In operation 1 e-15, the UE may restart the first timer every time thatthe UE transmits or receives data.

In operation 1 e-20, the UE may change from the connected mode to theidle mode if the first timer expires. If the second timer expires, theUE may report “periodic RNA update” to a BS that the UE currently campson (camp-on).

FIG. 1F is a flowchart illustrating operation of a BS according to anembodiment of the disclosure.

In operation 1 f-05, a BS configures a first timer for a predeterminedUE using a predetermined RRC message.

In operation 1 f-10, the BS configures a second timer for the UE using apredetermined RRC message.

In operation 1 f-15, the BS indicates the UE's transition to an idlemode or an inactive mode using an RRC connection release message. The BSmay include configuration information associated with the second timerin the connection release message.

In operation 1 f-20, if the RRC connection release message indicatestransition to the idle mode, the BS transmits the message to the UE, andafter a predetermined period of time, at least greater than 0 ms, the BSmay regard that the UE is changed to the idle mode irrespective ofwhether the second timer operates.

In operation 1 f-25, if the RRC connection release message indicatestransition to the inactive mode, the BS transmits the message to the UEand operates the second timer. The BS may operate the second timerbefore the RRC connection release message is received.

In operation 1 f-30, the BS monitors whether “periodic RNA update” istransmitted from the UE at a periodic RNA update timing that arrives forthe first time (or at the point in time at which the second timerexpires for the first time) after transmitting the RRC connectionrelease message. After the second timer expires, the BS may monitor the“periodic RNA update” during a predetermined period of time. The BS mayreceive “periodic RNA update” from another BS.

In operation 1 f-35, the BS may determine whether the “periodic RNAupdate” is successfully received.

If the “periodic RNA update” is successfully received, the BS may regardthat the UE successfully receives the connection release message and isalready in the inactive mode state in operation 1 f-40.

If the “periodic RNA update” is not successfully received even after thepredetermined period of time elapses, the BS may regard that the UE doesnot successfully receive the connection release message, may determinewhether the first timer expires, and may determine that the UE is stillin the connected mode or the idle mode in operation 1 f-45. If the firsttimer value does not elapse from the point in time at which the lastdata transmission or reception is successfully performed with the UE,the BS may regard that the UE is still in the connected mode. Since theUE is still in the connected mode, the BS is capable of retransmitting aconnection release message to the UE. If retransmission is triggered,the BS that the UE currently camps on may transmit the connectionrelease message to the UE. If the BS does not perform an operation oftransmitting the connection release message, the first timer may expire,and thus, the BS automatically regards that the UE is in the idle mode.Otherwise, if the first timer value elapses from the point in time atwhich the last data transmission or reception is successfully performedwith the UE, the BS may regard that the UE is in the idle mode.

FIG. 1G is a flowchart illustrating a process of transmitting an ACKsignal by a UE if the UE receives a connection release message accordingto an embodiment of the disclosure.

A UE 1 g-05 may receive the value of a first timer and the value of asecond timer via a predetermined RRC message from a BS 1 g-10, inoperation 1 g-15. The UE may operate the first timer at the point intime at which the timer value is received or at the point in time atwhich the timer value is received and first data is transmitted orreceived in operation 1 g-20, and may restart the first timer inoperation 1 g-30 every time that the UE transmits or receives data inoperation 1 g-25. If the UE successfully receives an RRC connectionrelease message from the BS in operation 1 g-35, the UE stops the firsttimer, and operates a third timer in operation 1 g-40. The value of thethird timer may be determined according to a predetermined rule, or maybe configured for the UE by the BS via a predetermined RRC message. Forexample, the value of the timer may be determined to beHARQ_RTT×NUMBER_OF_HARQ_RETX, or may be a previously defined fixedvalue. Here, HARQ_RTT denotes a round trip time in HARQ, andNUMBER_OF_HARQ_RETX denotes the maximum number of retransmissions inHARQ. Although the UE successfully receives the RRC connection releasemessage, the UE may maintain a connected mode until the third timerexpires. Until the third timer expires, the UE reports an ACK associatedwith the RRC connection release message to the BS in operation 1 g-50.If the third timer expires in operation 1 g-65, the UE stops ACKtransmission, and may change to an idle mode or inactive mode indicatedby the connection release message in operation 1 g-68. After firsttransmission of the RRC connection release message, the BS operates thethird timer in operation 1 g-45. Until the third timer expires, the BSretransmits the connection release message in operation 1 g-55. If thethird timer expires in operation 1 g-70, the BS regards that the UE ischanged to the idle mode or the inactive mode indicated by the RRCconnection release message in operation 1 g-75. If the RRC connectionrelease message indicates the inactive mode, the BS operates the secondtimer in operation 1 g-85 when the RRC connection release message istransmitted for the first time. If the second timer expires 1 g-90 and“periodic RNA update” of the UE is not received from the UE or anotherBS, the BS may regard that the UE is changed from the inactive mode tothe idle mode in operation 1 g-80.

FIG. 1H is a diagram illustrating the structure of a UE according to anembodiment of the disclosure.

Referring to the drawing, the UE includes a radio frequency (RF)processor 1 h-10, a baseband processor 1 h-20, a storage 1 h-30, and acontroller 1 h-40.

The RF processor 1 h-10 performs a function for transmitting orreceiving a signal via a wireless channel, such as band conversion andamplification of a signal. That is, the RF processor 1 h-10 up-convertsa baseband signal provided from the baseband processor 1 h-20 into an RFband signal, transmits the RF band signal via an antenna, anddown-converts an RF band signal received via the antenna into a basebandsignal. For example, the RF processor 1 h-10 may include a transmissionfilter, a reception filter, an amplifier, a mixer, an oscillator, adigital-to-analog converter (DAC), an analog-to-digital Converter (ADC),and the like. Although the drawing illustrates only a single antenna,the UE may include a plurality of antennas. In addition, the RFprocessor 1 h-10 may include a plurality of RF chains. Moreover, the RFprocessor 1 h-10 may perform beamforming. For the beamforming, the RFprocessor 1 h-10 may control the phase and the size of each signaltransmitted or received via a plurality of antennas or antenna elements.In addition, the RF processor may perform MIMO, and may receive multiplelayers when performing an MIMO operation.

The baseband processor 1 h-20 performs a function for conversion betweena baseband signal and a bitstream according to the physical layerstandard of a system. For example, in the case of data transmission, thebaseband processor 1 h-20 encodes and modulates a transmissionbitstream, so as to produce complex symbols. In addition, in the case ofdata reception, the baseband processor 1 h-20 restores a receptionbitstream by demodulating and decoding a baseband signal provided fromthe RF processor 1 h-10. For example, according to an orthogonalfrequency division multiplexing (OFDM) scheme, in the case of datatransmission, the baseband processor 1 h-20 produces complex symbols byencoding and modulating a transmission bitstream, maps the complexsymbols onto subcarriers, and then configures OFDM symbols via aninverse fast Fourier transform (IFFT) operation and cyclic prefix (CP)insertion. Further, in the case of data reception, the basebandprocessor 1 h-20 divides a baseband signal provided from the RFprocessor 1 h-10 in units of OFDM symbols, reconstructs signals mappedonto subcarriers via a fast Fourier transform (FFT) operation, and thenreconstructs a reception bitstream via demodulation and decoding.

The baseband processor 1 h-20 and the RF processor 1 h-10 transmit andreceive signals as described above. Accordingly, the baseband processor1 h-20 and the RF processor 1 h-10 may be referred to as a transmitter,a receiver, a transceiver, or a communication unit. Furthermore, atleast one of the baseband processor 1 h-20 and the RF processor 1 h-10may include a plurality of communication modules in order to supportmultiple different radio access technologies. In addition, at least oneof the baseband processor 1 h-20 and the RF processor 1 h-10 may includedifferent communication modules to process signals of differentfrequency bands. For example, the different radio access technologiesmay include a wireless LAN (e.g., IEEE 802.11), a cellular network(e.g., LTE), and the like. Further, the different frequency bands mayinclude a super high frequency (SHF) (e.g., 2.NRHz, NRhz) band and amillimeter (mm) wave (e.g., 60 GHz) band.

The storage 1 h-30 stores data such as a basic program, an applicationprogram, and configuration information for operation of the UE.Particularly, the storage 1 h-30 may store information related to asecond access node that performs wireless communication using a secondradio access technology. In addition, the storage 1 h-30 provides datastored therein in response to a request from the controller 1 h-40.

The controller 1 h-40 controls overall operation of the UE. For example,the controller 1 h-40 may perform transmission or reception of a signalvia the baseband processor 1 h-20 and the RF processor 1 h-10. Inaddition, the controller 1 h-40 may record data in the storage 1 h-40and may read the data. To this end, the controller 1 h-40 may include atleast one processor. For example, the controller 1 h-40 may include acommunication processor (CP) that performs control for communication,and an application processor (AP) that controls a higher layer such asan application program. The controller 1 h-40 may further include amulti-connection processor 1 h-42 for supporting multiple connections.

FIG. 1I is a block diagram of a BS in a wireless communication systemaccording to an embodiment of the disclosure.

As illustrated in the drawing, the BS may include an RF processor 1i-10, a baseband processor 1 i-20, a backhaul communication unit 1 i-30,a storage 1 i-40, and a controller 1 i-50.

The RF processor 1 i-10 performs a function for transmitting orreceiving a signal via a wireless channel, such as band conversion andamplification of a signal. That is, the RF processor 1 i-10 up-convertsa baseband signal provided from the baseband processor 1 i-20 into an RFband signal, transmits the RF band signal via an antenna, anddown-converts an RF band signal received via the antenna into a basebandsignal. For example, the RF processor 1 i-10 may include a transmissionfilter, a reception filter, an amplifier, a mixer, an oscillator, a DAC,an ADC, and the like. Although the drawing illustrates only a singleantenna, the BS may include a plurality of antennas. In addition, the RFprocessor 1 i-10 may include a plurality of RF chains. Moreover, the RFprocessor 1 i-10 may perform beamforming. For the beamforming, the RFprocessor 1 i-10 may control the phase and the size of each of thesignals transmitted or received via a plurality of antennas or antennaelements. The RF processor may perform a downlink MIMO operation bytransmitting one or more layers.

The baseband processor 1 i-20 performs a function for conversion betweena baseband signal and a bitstream according to the physical layerstandard of a first radio access technology. For example, in the case ofdata transmission, the baseband processor 1 i-20 encodes and modulates atransmission bitstream, so as to produce complex symbols. In addition,in the case of data reception, the baseband processor 1 i-20 restores areception bitstream by demodulating and decoding a baseband signalprovided from the RF processor 1 i-10. For example, according to theOFDM scheme, in the case of data transmission, the baseband processor 1i-20 may produce complex symbols by encoding and modulating atransmission bitstream, map the complex symbols onto subcarriers, andthen configure OFDM symbols via an IFFT operation and CP insertion.Further, in the case of data reception, the baseband processor 1 i-20divides a baseband signal provided from the RF processor 1 i-10 in unitsof OFDM symbols, reconstructs signals mapped onto the subcarriers via anFFT operation, and then reconstructs a reception bitstream viademodulation and decoding. The baseband processor 1 h-20 and the RFprocessor 1 i-10 transmit and receive signals as described above.Accordingly, the baseband processor 1 i-20 and the RF processor 1 i-10may be referred to as a transmitter, a receiver, a transceiver, acommunication unit, or a wireless communication unit.

The backhaul communication unit 1 i-30 may provide an interface forperforming the communication with other nodes in a network. That is, thebackhaul communication unit 1 i-30 may convert, into a physical signal,a bitstream transmitted from the BS to another node, for example, asecondary BS, a core network, and the like, and may convert a physicalsignal received from the other node into a bitstream.

The storage 1 i-40 stores data such as a basic program, an applicationprogram, and configuration information for operation of the master BS.Particularly, the storage 1 i-40 may store information associated with abearer allocated to a connected UE, a measurement result reported from aconnected UE, and the like. In addition, the storage 1 i-40 may storeinformation which is a criterion for determining whether to provide orsuspend multiple connections to a UE In addition, the storage 1 i-40provides data stored therein in response to a request from thecontroller 1 i-50.

The controller 1 i-50 may control overall operation of the BS. Forexample, the controller 1 i-50 may transmit or receive a signal via thebaseband processor 1 i-20 and the RF processor 1 i-10, or via thebackhaul communication unit 1 i-30. In addition, the controller 1 i-50may record data in the storage 1 i-40 and read the data. To this end,the controller 1 i-50 may include at least one processor. The controllermay further include a multi-connection processor 1 i-52 for supportingmultiple connections.

Second Embodiment

FIG. 2A is a diagram illustrating an LTE BS connected to a nextgeneration mobile communication network.

A legacy LTE BS 2 a-15 is connected to an MME 2 a-05 which is a singlenetwork entity. Conversely, to a next generation mobile communicationnetwork (NG core) 2 a-10, a next generation mobile communication BS maybe connected. However, a legacy LTE BS may be upgraded and may beconnected to the next generation mobile communication network. Theupgraded LTE BS is referred to as an evolved/enhanced LTE (eLTE) BS 2a-20. The eLTE BS may be connected to a legacy MME or a next generationmobile communication network (NG core), or may be connected to both. Ifthe eLTE BS is connected only to the NG core, only a UE 2 a-30 thatsupports eLTE may be connected to the eLTE BS, and may be capable ofperforming communication with the next generation mobile communicationnetwork. Conversely, although a legacy UE 2 a-25 attempts to connect tothe eLTE BS, the legacy UE 2 a-25 is incapable of performingcommunication with the next generation mobile communication network.Therefore, the legacy UE needs to be prevented from camping on the eLTEBS that is only connected to the NG core. If the eLTE BS is connectedboth the NG core and EPC, the BS may support both a UE that supportseLTE and a legacy UE. Connection to a network supportable by acorresponding UE may be established for each UE.

FIG. 2B is a diagram illustrating a method of determining whether togrant access in a legacy LTE system. The inside of an LTE UE is dividedinto an access stratum (AS) 2 b-15 and a non access stratum (NAS) 2 b-05from the perspective of a function. The AS performs all functionsrelated to access, and the NAS performs functions irrelevant to access,such as selecting a public land mobile network (PLMN), requesting aservice, or the like. Whether access is available is mainly determinedin the UE AS. A network may limit new access if the network iscongested. To this end, the network may broadcast related configurationinformation so that each UE is capable of determining whether access isavailable in operation 2 b-35. In the legacy LTE system, a new barringmechanism is also proposed as new requirements are added. Accordingly,the UE needs to perform a plurality of access check procedures (accessbarring check). If the UE NAS transfer a service request 2 b-10 to theUE AS, the UE AS may check whether access is available in order todetermine whether access to the network is actually available, inresponse to the request. If the establishment cause value of the servicerequest is “delay tolerant access”, the UE AS may perform extendedaccess barring (EAB) 2 b-20 first. The EAB barring mechanism is anaccess check procedure applied only to a machine type communication(MTC) device. After the EAB, the UE AS may perform application specificcongestion control for data communication (ACDC) 2 b-20 or access classbarring (ACB) 2 b-30. An application of which the service is requestedmay be assigned with a single piece of ACDC category information, andthe value of the ACDC category may be provided to the UE AS by beingincluded in the service request. The network may provide barringconfiguration information for each ADCD category. That is, the UE AS mayperform access check procedure for each application group classifiedbased on an ACDC category. If the barring configuration informationassociated with the ACDC category is not provided from the network, theUE AS may omit the ACDC access check procedure. The UE AS may performaccess class barring (ACB) 2 b-30. The ACB is an access check procedureperformed using barring configuration information separately providedaccording to mobile originating data (MO) or MO signaling. Formultimedia telephony (MINITEL) voice/video/short message service (SMS),the procedure of performing ACB may be omitted using an ACB skipindicator in operation 2 b-25. If it is determined that all of theabove-mentioned plurality of access check procedures result in“accessible”, the UE AS may attempt to access the network. That is, theUE AS performs random access, and may transmit an RRC connection requestmessage 2 b-40 to the BS. There is an access check procedure that the UEAS does not perform. If the UE AS receives barring configurationinformation 2 b-45 (S SAC) associated with the MINITEL voice/video fromthe network, the UE AS may transfer the same to an IP multimediasubsystem (IMS) layer 2 b-50 in the UE which manages the service. TheIMS layer that receives the barring configuration information mayperform an access check procedure when the service is triggered. When aservice specific access class (SSAC) was introduced, the UE AS wasdesigned to perform a function irrespective of the type of applicationor service. Therefore, in order to control whether to grant access inassociation with only a predetermined service such as MMTEL voice/videoor the like, barring configuration information needs to be directlytransferred to a layer that manages the corresponding service, so thatthe layer performs an access check procedure.

For example, in the legacy LTE system, the ACDC was proposed for thepurpose of determining whether access is available for each application(service). Each application is assigned with at least one ACDC categoryvalue. The ACDC category is a value between 1 to 16. The network mayprovide corresponding ACDC category information for each application tothe UE NAS using a NAS message. The network may provide barringconfiguration information applied to a corresponding ACDC category usingsystem information block type 2 (SIB2). The barring configurationinformation may include an ac-BarringFactor IE and an ac-Barringtime IE.The ac-BarringFactor α is in the range of 0≤α<1. The UE AS obtains“rand” which is a random value in the range of 0≤rand<1. If the randomvalue is less than ac-BarringFactor, it is determined that access is notbanned. Otherwise, it is determined that access is banned. If it isdetermined that access is banned, the UE AS delays attempting accessduring a predetermined period of time obtained using Equation 1 givenbelow.

“Tbarring”=(0.7+0.6*rand)*ac-BarringTime.  [Equation 1]

If a service request is triggered by the UE NAS, the UE AS may obtain anACDC category value corresponding to an application desired to beserviced. In addition, if the UE NAS transfers the service request tothe UE AS, the obtained ACDC category value may be included therein andmay be transferred to the UE AS. The UE AS that receives the servicerequest may determine whether to grant access using the ACDC barringconfiguration information included in the SIB2, based on the ACDCcategory value. If the barring configuration information correspondingto the ACDC category does not exist in the SIB2, the UE AS regards thataccess of the application associated with the ACDC category has beengranted in the ACDC procedure. If access is granted via the access grantcheck procedures, the UE AS performs random access to the network andtransmits an RRC connection request message in operation 2 b-40.

FIG. 2C is a diagram illustrating a process of performing UE accesscontrol according to the disclosure. In the disclosure, there isprovided an access control scheme based on an access identity and anaccess category, similarly to a legacy ACDC. An access identity isindication information defined in 3GPP, that is, indication informationclearly mentioned in the standard document. The access identity is usedfor indicating predetermined access, as shown in Table 1 provided below.The access identity indicates accesses classified based on accessclasses 11 to 15, a multimedia priority service (MPS), and a missioncritical service (MCS). The access classes 11 to 15 indicate dedicatedaccesses for a business operator or a person interested, or for publicpurpose.

TABLE 1 Access Identity number UE configuration 0 UE is not configuredwith any parameters from this table  1 (NOTE 1) UE is configured forMultimedia Priority Service (MPS).  2 (NOTE 2) UE is configured forMission Critical Service (MCS). 3-10 Reserved for future use 11 (NOTE 3)Access Class 11 is configured in the UE. 12 (NOTE 3) Access Class 12 isconfigured in the UE. 13 (NOTE 3) Access Class 13 is configured in theUE. 14 (NOTE 3) Access Class 14 is configured in the UE. 15 (NOTE 3)Access Class 15 is configured in the UE. (NOTE 1): Access Identity 1 isused to provide overrides according to the subscription information inUEs configured for MPS. subscription information defines whether anoveride applies to UEs within one of the following categories: a) UEsthat are configured for MPS; b) UEs that are configured for MPS and arein the PLMN listed as most preferred PLMN of the country where the UE isroaming in the operator-defined PLMN selector list or in their HPLMN orin a PLMN that is equivalent to their HPLMN; c) UEs that are configuredfor MPS and are in their HPLMN or in a PLMN that is equivalent to it.(NOTE 2): Access Identity 2 is used to provide overrides according tothe subscription information in UEs configured for MCS. The subscriptioninformation defines whether an overide applies to UEs within one of thefollowing categories: a) UEs that are configured for MCS; b) UEs thatare configured for MCS and are in the PLMN listed as most preferred PLMNof the country where the UE is roaming in the operator-defined PLMNselector list or in their HPLMN or in a PLMN that is equivalent to theirHPLMN; c) UEs that are configured for MCS and are in their HPLMN or in aPLMN that is equivalent to it. (NOTE 3): Access Identities 11 and 15 arevalid in Home PLMN only if the EHPLMN list is not present or in anyEHPLMN. Access Identities 12, 13 and 14 are valid in Home PLMN andvisited PLMNs of home country only. For this purpose the home country isdefined as the country of the MCC part of the IMSI

The access category is divided into two classes. One is a “standardizedaccess category”. The standardized access category is a category definedin an RAN level, that is, a category that is clearly mentioned in thestandard document. Therefore, the same standardized access category isapplied to different business operators. In the disclosure, a categorycorresponding to “emergency” falls within the standardized accesscategory. All accesses may correspond to at least one included in thestandardized access category. The other is an “operator-specific (i.e.,non-standardized) access category”. The operator-specific category isdefined outside 3GPP, and is not specified in the standardized document.Therefore, an operator-specific access category indicates a differentmeaning for each operator. This is the same characteristic as that of acategory in the legacy ACDC. An access triggered by a UE NAS may not bemapped onto an operator-specific access category. A big difference fromthe legacy ACDC is that the category corresponds not only to anapplication, but also to factors other than the application, that is, aservice type, a call type, a UE type, a user group, a signaling type, aslice type, or a combination of the factors. That is, according to anaccess category, a UE AS may control whether to grant access inassociation with accesses corresponding to other factors other than anapplication. The access category is used for indicating predeterminedaccess, as shown in Table 2 provided below. Access categories #0 to 7are used for indicating a “standardized access category”, and accesscategories #32 to 63 are used for indicating an “operator-specificaccess category”.

TABLE 2 Access Category number Conditions related to UE Type of accessattempt 0 All MO signalling resulting from paging 1 (NOTE 1) UE isconfigured for delay tolerant All except for Emergency service andsubject to access control for Access Category 1, which is judged basedon relation of UE's HPLMN and the selected PLMN. 2 All Emergency 3 Allexcept for the conditions in MO signalling resulting from other thanAccess Category 1. paging 4 All except for the conditions in MMTEL voiceAccess Category 1. 5 All except for the conditions in MMTEL video AccessCategory 1. 6 All except for the conditions in SMS Access Category 1. 7All except for the conditions in MO data that do not belong to any otherAccess Category 1. Access Categories  8-31 Reservedstandardized AccessCategories 32-63 All Based on operator classification (NOTE 2) (NOTE 1):The barring parameter for Access Category 1 is accompanied withinformation that define whether Access Category applies to UEs withinone of the following categories: a) UEs that are configured for delaytolerant service; b) UEs that are configured for delay tolerant serviceand are neither in their HPLMN nor in a PLMN that is equivalent to it;c) UEs that are configured for delay tolerant service and are neither inthe PLMN listed as most preferred PLMN of the country where the UE isroaming in the operator-defined PLMN selector list on the SIM/USIM, norin their HPLMN nor in a PLMN that is equivalent to their HPLMN. (NOTE2): When there are an Access Category based on operator classificationand a standardized Access Category to both of which an access attemptcan be categorized, and the standardized Access Category is neither 0nor 2, the UE applies the Access Category based on operatorclassification. When there are an Access Category based on operatorclassification and a standardized Access Category to both of which anaccess attempt can be categorized, and the standardized Access Categoryis 0 or 2, the UE applies the standardized Access Category.

An operator server 2 c-25 may provide information (management object(MO)) associated with operator-specific access category information tothe UE NAS via NAS signaling or application level data transmission. Theinformation may indicate a factor, such as an application or the like,which corresponds to a corresponding operator-specific category. Forexample, the information may include that access category #32corresponds to an access that corresponds to the Facebook application. AgNB 2 c-20 provides a list of categories of which barring configurationinformation are provided, and barring configuration informationcorresponding to a corresponding category to UEs via system information.A UE 2 c-05 includes logical blocks of an NAS 2 c-10 and an AS 2 c-15.The UE NAS may map a triggered access onto one or more access identitiesand one access category, according to a predetermined rule. According toanother option, in the access category mapping process, one access ismapped onto one standardized access category, and additionally, may bemapped onto an operator-specific access category. The UE NAS transfers,to the UE AS, the mapped access identity and access category togetherwith a service request. The UE AS determines whether the accesstriggered by the UE NAS is allowed (i.e., barring check), using thebarring configuration information.

If both EPC and 5GC are connected to an eLTE BS, the eLTE BS may supportboth a legacy UE and an eLTE UE. The legacy UE may determine whetheraccess is allowed, using the above-described LTE access controlmechanism. In the LTE system, barring configuration information isprovided to UEs via SIB2. In the disclosure, this is referred to as LTEbarring configuration information. Conversely, the eLTE UE may determinewhether access is allowed, using the above-described next generationmobile communication NR access control mechanism. Barring configurationinformation applied in NR access control is different from barringconfiguration information applied in LTE. In the disclosure, this isreferred to as NR barring configuration information. Therefore, if theeLTE BS is capable of supporting both the legacy UE and the eLTE UE, theeLTE BS needs to provide two types of barring configuration informationto two types of UEs using system information. In the disclosure, thereis provided a method of providing the two types of barring configurationinformation to UE by including the same in SIB2 or SIBx that only theeLTE UE is capable of understanding, depending on whether the eLTE BS iscapable of supporting only the eLTE UE or supporting both the legacy UEand the eLTE UE. Particularly, if the eLTE BS supports only the eLTE UE,the eLTE BS includes NR barring configuration information in the SIBx orSIB2. If the eLTE BS is capable of supporting both the legacy UE and theeLTE UE, the eLTE BS includes LTE barring configuration information inSIB2 and includes NR barring configuration information in SIBx.

The SIB2 is system information that both the legacy UE and the eLTE UEare capable of understanding. However, if both the LTE barringconfiguration information and the NR barring configuration informationare included in SIB2, the size of SIB2 may be increased. The amount ofinformation that each SIB is capable of storing is limited. Therefore,depending on the size of barring configuration information to beprovided, SIB2 may not store the entirety of the barring configurationinformation. In addition, even through NR barring configurationinformation is included in SIB2, it is unnecessary information for thelegacy UE. The legacy UE is incapable of understanding the NR barringconfiguration information. Therefore, in the disclosure, if the eLTE BSis capable of supporting both the legacy UE and the eLTE UE, LTE barringconfiguration information is included in SIB2, and NR barringconfiguration information is included in SIBx. The eLTE UE is capable ofunderstanding the SIBx. However, the legacy UE is incapable ofunderstanding the SIBx and may not need to receive the same. SIB1includes scheduling information associated with SIBx, and the legacy UEis incapable of understanding the scheduling information associated withthe SIBx included in the SIB1. The eLTE UE may identify the location ofa radio resource in which SIBx is transmitted, by taking intoconsideration both scheduling information associated with existing SIBsand the scheduling information associated with SIBx, included in SIB1.In the case in which the eLTE BS supports only the eLTE UE, LTE barringconfiguration information may not need to be provided. Therefore, it isno burden for SIB2 to store NR barring configuration information. Inthis instance, the eLTE BS may include the NR barring configuration inSIB2. Alternatively, for unity, the eLTE BS may always include NRbarring configuration information in SIBx, irrespective of whether theeLTE BS supports the legacy UE. However, in this instance, thescheduling information associated with SIBx needs to be included inSIB1.

FIG. 2D is a flowchart illustrating an operation of providing accessconfiguration information by a BS according to an embodiment of thedisclosure.

In operation 2 d-05, an eLTE BS determines whether the eLTE BS isconnected to both EPC and 5GC, and whether the eLTE BS supports both alegacy UE and an eLTE UE.

In operation 2 d-10, if the eLTE BS is connected to both EPC and 5GC,and supports both the legacy UE and the eLTE UE, the eLTE BS stores LTEbarring configuration information in SIB2. The eLTE BS additionallystores scheduling information associated with SIBx in SIB1. Forreference, SIB2 belongs to essential SIB in LTE, and thus SIB1 alwaysincludes scheduling information associated with SIB2. The eLTE BS maystore NR barring configuration information in SIBx. The eLTE BS maybroadcast the configured Ms.

In operation 2 d-15, if the eLTE BS is connected to only 5GC, andsupports only the eLTE UE, the eLTE BS may store LTE barringconfiguration information in SIB2. As another option, schedulinginformation associated with SIBx is additionally stored in SIB1, and NRbarring configuration information is stored in SIBx. The eLTE BS maybroadcast the configured SIB s.

FIG. 2E is a flowchart illustrating an operation of receiving andapplying access configuration information by an eLTE UE according to anembodiment of the disclosure.

In operation 2 e-01, the eLTE UE is capable of communicating with eLTEconnected to 5GC. The UE determines whether an LTE BS that the UEcurrently camps on is connected to only EPC. The UE may recognizewhether the LTE BS is connected to EPC or 5GC, or is connected to both,based on PLMN information provided via system information. Each PLMNcorresponds to one of EPC or 5GC. An LTE BS that is connected to onlyEPC, is capable of supporting only a legacy UE. Accordingly, the eLTE UEmay camp on the LTE BS as a legacy UE. If the eLTE UE does not include alegacy UE function, the eLTE UE is incapable of communicating with theLTE BS that is connected to only EPC, and needs to search for another BSto camp on.

In operation 2 e-05, if the LTE BS is connected to 5GC or is connectedto both 5GC and EPC, the UE may receive and store LTE barringconfiguration information and NR barring configuration information fromSIBx and SIB2 broadcasted from the BS.

In operation 2 e-10, the UE may determine one of 5GC or EPC foraccessing. If the BS is connected to only 5GC, the UE may select only5GC.

In operation 2 e-15, if EPC is selected, the UE may apply LTE barringconfiguration information.

In operation 2 e-20, if access is triggered, the UE may perform barringcheck using the LTE barring configuration information.

In operation 2 e-25, the UE may perform a connection establishmentprocess with respect to the BS if it is identified that access isallowed via the barring check.

In operation 2 e-30, if 5GC is selected, the UE may apply NR barringconfiguration information.

In operation 2 e-35, if access is triggered, the UE may perform barringcheck using the NR barring configuration information.

In operation 2 e-40, the UE may perform a connection establishmentprocess with respect to the BS if it is identified that access isallowed via the barring check.

In operation 2 e-45, the UE receives and store LTE barring configurationinformation from SIB2 broadcasted from the BS.

In operation 2 e-50, if EPC is selected, the UE may apply LTE barringconfiguration information.

In operation 2 e-55, if access is triggered, the UE may perform barringcheck using the LTE barring configuration information.

In operation 2 e-60, the UE may perform a connection establishmentprocess with respect to the B S if it is identified that access isallowed via the barring check.

FIG. 2F is a diagram illustrating the structure of a UE according to anembodiment of the disclosure.

Referring to the drawing, the UE includes a radio frequency (RF)processor 2 f-10, a baseband processor 2 f-20, a storage 2 f-30, and acontroller 2 f-40.

The RF processor 2 f-10 performs a function for transmitting orreceiving a signal via a wireless channel, such as band conversion andamplification of a signal. That is, the RF processor 2 f-10 up-convertsa baseband signal provided from the baseband processor 2 f-20 into an RFband signal, transmits the RF band signal via an antenna, anddown-converts an RF band signal received via the antenna into a basebandsignal. For example, the RF processor 2 f-10 may include a transmissionfilter, a reception filter, an amplifier, a mixer, an oscillator, adigital-to-analog converter (DAC), an analog-to-digital converter (ADC),and the like. Although the drawing illustrates only a single antenna,the UE may include a plurality of antennas. In addition, the RFprocessor 2 f-10 may include a plurality of RF chains. Moreover, the RFprocessor 2 f-10 may perform beamforming. For the beamforming, the RFprocessor 2 f-10 may control the phase and the size of each signaltransmitted or received via a plurality of antennas or antenna elements.In addition, the RF processor may perform MIMO, and may receive multiplelayers when performing an MIMO operation.

The baseband processor 2 f-20 performs a function for conversion betweena baseband signal and a bitstream according to the physical layerstandard of a system. For example, in the case of data transmission, thebaseband processor 2 f-20 encodes and modulates a transmissionbitstream, so as to produce complex symbols. In addition, in the case ofdata reception, the baseband processor 2 f-20 restores a receptionbitstream by demodulating and decoding a baseband signal provided fromthe RF processor 2 f-10. For example, according to an orthogonalfrequency division multiplexing (OFDM) scheme, in the case of datatransmission, the baseband processor 2 f-20 produces complex symbols byencoding and modulating a transmission bitstream, maps the complexsymbols onto subcarriers, and then configures OFDM symbols via aninverse fast Fourier transform (IFFT) operation and cyclic prefix (CP)insertion. Further, in the case of data reception, the basebandprocessor 2 f-20 divides a baseband signal provided from the RFprocessor 2 f-10 in units of OFDM symbols, reconstructs signals mappedonto subcarriers via a fast Fourier transform (FFT) operation, and thenreconstructs a reception bitstream via demodulation and decoding.

The baseband processor 2 f-20 and the RF processor 2 f-10 transmit andreceive signals as described above. Accordingly, the baseband processor2 f-20 and the RF processor 2 f-10 may be referred to as a transmitter,a receiver, a transceiver, or a communication unit. Furthermore, atleast one of the baseband processor 2 f-20 and the RF processor 2 f-10may include a plurality of communication modules in order to supportdifferent multiple radio access technologies. In addition, at least oneof the baseband processor 2 f-20 and the RF processor 2 f-10 may includedifferent communication modules to process signals of differentfrequency bands. For example, the different radio access technologiesmay include a wireless LAN (e.g., IEEE 802.11), a cellular network(e.g., LTE), and the like. Further, the different frequency bands mayinclude a super high frequency (SHF) (e.g., 2.NRHz, NRhz) band and amillimeter (mm) wave (e.g., 60 GHz) band.

The storage 2 f-30 stores data such as a basic program, an applicationprogram, and configuration information for the operation of the UE.Particularly, the storage 2 f-30 may store information related to asecond access node that performs wireless communication using a secondradio access technology. In addition, the storage 2 f-30 provides datastored therein in response to a request from the controller 2 f-40.

The controller 2 f-40 controls overall operation of the UE. For example,the controller 2 f-40 may perform transmission or reception of a signalvia the baseband processor 2 f-20 and the RF processor 2 f-10. Inaddition, the controller 2 f-40 may record data in the storage 2 f-40and read the data. To this end, the controller 2 f-40 may include atleast one processor. For example, the controller 2 f-40 may include acommunication processor (CP) that performs control for communication,and an application processor (AP) that controls a higher layer such asan application program. The controller 2 f-40 may further include amulti-connection processor 2 f-42 for supporting multiple connections.

FIG. 2G is a block diagram of a BS in a wireless communication systemaccording to an embodiment of the disclosure.

As illustrated in the drawing, the BS may include an RF processor 2g-10, a baseband processor 2 g-20, a backhaul communication unit 2 g-30,a storage 2 g-40, and a controller 2 g-50.

The RF processor 2 g-10 performs a function for transmitting orreceiving a signal via a wireless channel, such as band conversion andamplification of a signal. That is, the RF processor 2 g-10 up-convertsa baseband signal provided from the baseband processor 2 g-20 into an RFband signal so as to transmit the RF band signal via an antenna, anddown-converts an RF band signal received via the antenna into a basebandsignal. For example, the RF processor 2 g-10 may include a transmissionfilter, a reception filter, an amplifier, a mixer, an oscillator, a DAC,an ADC, and the like. Although the drawing illustrates only a singleantenna, the first access node may include a plurality of antennas. Inaddition, the RF processor 2 g-10 may include a plurality of RF chains.Moreover, the RF processor 2 g-10 may perform beamforming. For thebeamforming, the RF processor 2 g-10 may control the phase and the sizeof each of the signals transmitted or received via a plurality ofantennas or antenna elements. The RF processor may perform a downlinkMIMO operation by transmitting one or more layers.

The baseband processor 2 g-20 performs a function for conversion betweena baseband signal and a bitstream according to the physical layerstandard of a first radio access technology. For example, in the case ofdata transmission, the baseband processor 2 g-20 encodes and modulates atransmission bitstream, so as to produce complex symbols. In addition,in the case of data reception, the baseband processor 2 g-20 restores areception bitstream by demodulating and decoding a baseband signalprovided from the RF processor 2 g-10. For example, according to theOFDM scheme, in the case of data transmission, the baseband processor 2g-20 may produce complex symbols by encoding and modulating atransmission bitstream, map the complex symbols onto subcarriers, andthen configure OFDM symbols via an IFFT operation and CP insertion.Further, in the case of data reception, the baseband processor 2 g-20divides a baseband signal provided from the RF processor 2 g-10 in unitsof OFDM symbols, reconstructs signals mapped onto the subcarriers via aFFT operation, and then reconstructs a reception bitstream viademodulation and decoding. The baseband processor 2 g-20 and the RFprocessor 2 g-10 transmit and receive signals as described above.Accordingly, the baseband processor 2 g-20 and the RF processor 2 g-10may be referred to as a transmitter, a receiver, a transceiver, acommunication unit, or a wireless communication unit.

The backhaul communication unit 2 g-30 may provide an interface forperforming communication with other nodes in a network. That is, thebackhaul communication unit 2 g-30 may convert, into a physical signal,a bitstream transmitted from the master BS to another node, for example,a secondary BS, a core network, and the like, and may convert a physicalsignal received from the other node into a bitstream.

The storage 2 g-40 stores data such as a basic program, an applicationprogram, and configuration information for the operation of the masterBS. Particularly, the storage 2 g-40 may store information associatedwith a bearer allocated to a connected UE, a measurement result reportedfrom a connected UE, and the like. In addition, the storage 2 g-40 maystore information which is a criterion for determining whether toprovide or suspend multiple connections to a UE. In addition, thestorage 2 g-40 provides data stored therein in response to a requestfrom the controller 2 g-50.

The controller 2 g-50 may control the overall operation of the masterBS. For example, the controller 2 g-50 may transmit or receive a signalvia the baseband processor 2 g-20 and the RF processor 2 g-10, or viathe backhaul communication unit 2 g-30. In addition, the controller 2g-50 may record data in the storage 2 g-40 and read the data. To thisend, the controller 2 g-50 may include at least one processor. Thecontroller 2 g-50 may further include a multi-connection processor 2g-52 for supporting multiple connections.

The embodiments of the disclosure described and shown in thespecification and the drawings have been presented to easily explain thetechnical contents of the embodiments of the disclosure and helpunderstanding of the embodiments of the disclosure, and are not intendedto limit the scope of the embodiments of the disclosure. Therefore, thescope of various embodiments of the disclosure should be construed toinclude, in addition to the embodiments disclosed herein, all changesand modifications derived on the basis of the technical idea of thedisclosure.

What is claimed is:
 1. A method performed by a base station in awireless communication system, the method comprising: identifyingwhether the base station is connected with both an evolved packet core(EPC) and a 5G core (5GC) and the base station supports both a legacyterminal and an eLTE terminal or whether the base station is connectedwith the 5GC and the base station supports the eLTE terminal; and incase that the base station is connected with both the EPC and the 5GC,transmitting, to a terminal, a first system information block (SIB)including first barring information for the EPC; and transmitting, tothe terminal, a second SIB different from the first SIB, the second SIBincluding second barring information for the 5GC.
 2. The method of claim1, wherein an access barring check is performed based on one of thefirst barring information for the EPC and the second barring informationfor the 5GC, according to a core network to which the terminal is toconnect.
 3. The method of claim 2, further comprising: establishing aradio resource control, RRC, connection with the terminal, according toa result of the access barring check.
 4. The method of claim 1, whereinthe first SIB is an SIB2, and the second SIB is an SIBx; and wherein thebase station is connected with a mobility management entity (MME) of theEPC and an access and mobility management function (AMF) entity of the5GC.
 5. The method of claim 1, wherein in case that the base station isconnected with the 5GC and the base station supports the eLTE terminal,further comprising: transmitting, to the terminal, a third SIB includingthe second barring information for the 5GC.
 6. The method of claim 5,wherein the first SIB and the third SIB are a SIB2 and the second SIB isan SIBx.
 7. A base station in a wireless communication system, atransceiver configured to transmit or receive a signal; and a controllerconfigured to: identify whether the base station is connected with bothan evolved packet core (EPC) and a 5G core (5GC) and the base stationsupports both a legacy terminal and an eLTE terminal or whether the basestation is connected with the 5GC and the base station supports the eLTEterminal; and in case that the base station is connected with both theEPC and the 5GC, transmit, to a terminal, a first system informationblock (SIB) including first barring information for the EPC; andtransmit, to the terminal, a second SIB different from the first SIB,the second SIB including second barring information for the 5GC.
 8. Thebase station of claim 7, wherein an access barring check is performedbased on one of the first barring information for the EPC and the secondbarring information for the 5GC, according to a core network to whichthe terminal is to connect.
 9. The base station of claim 8, thecontroller is further configured to: establish a radio resource control,RRC, connection with the terminal, according to a result of the accessbarring check.
 10. The base station of claim 7, wherein the first SIB isan SIB2, and the second SIB is an SIBx; and wherein the base station isconnected with a mobility management entity (MME) of the EPC and anaccess and mobility management function, AMF, entity of the 5GC.
 11. Thebase station of claim 7, wherein in case that the base station isconnected with the 5GC and the base station supports the eLTE terminal,the controller is further configured to: transmit, to the terminal, athird SIB including the second barring information for the 5GC.
 12. Thebase station of claim 11, wherein the first SIB and the third SIB are aSIB2 and the second SIB is an SIBx.